Lily Allen is seen leaving the UNICEF Halloween ball, held at 1 Mayfair on October 31, 2013 in London, England. (Photo by Niki Nikolova/FilmMagic)

Demi Lovato as a skeleton.

Matt Lauer dresses as Pam Anderson's character from "Baywatch" on NBC's "Today" Halloween show on Thursday, Oct. 31, 2013 in New York.

It's hard to recognize these actresses with their fishermen costumes.

Host Kenan Thompson speaks on stage at "Hub Network's First Annual Halloween Bash" on Sunday, Oct. 20, 2013, at the Barker Hanger in Santa Monica, Calif. The star-studded special will be broadcasted on the Hub Network on Saturday Oct. 26, 2013. (Photo by Jordan Strauss/Invision for the Hub Network/AP Images)

Kathie Lee Gifford, left, and Hoda Kotb dress as Wilma and Betty from the "Flintstones" on NBC's "Today" Halloween show on Thursday, Oct. 31, 2013 in New York. (Photo by Charles Sykes/Invision/AP)

Jenni "JWoww" Farley, left, and Nicole "Snooki" Polizzi attend Night of the Living Drag: A RuPaul's Drag Race Halloween party on Friday, Oct. 25, 2013 in New York. (Photo by Charles Sykes/Invision/AP)

WEST HOLLYWOOD, CA - OCTOBER 31: Singer/actress Demi Lovato attends her Halloween Party at the PhilyMack Management Building on October 31, 2013 in West Hollywood, California. (Photo by Christopher Polk/Getty Images for Philymack)

Beyonce as an angel.

Billy Gardell as Frankenstein and Melissa McCarthy as bride of Frankenstein.

Naya Rivera as Carmen Sandiego.

NEW YORK - OCTOBER 30: Nick Cannon and Mariah Carey attend a Halloween party at Marquee on October 30, 2008 in New York City. (Photo by Johnny Nunez/WireImage)

NEW YORK - OCTOBER 30: Singer Mariah Carey and actor Nick Cannon attend their Halloween Eve Costume Party at Marquee on October 30, 2008 in New York City. (Photo by Stephen Lovekin/WireImage for Syndicate)

WHIPPANY, NJ - OCTOBER 24: (EXCLUSIVE ACCESS, SPECIAL RATES APPLY) Television personality Nicole 'Snooki' Polizzi, Jionni Lavalle and their son Lorenzo Lavalle celebrate Halloween in their costumes from Rubies Costume Company on October 24, 2013 in Whippany, New Jersey. (Photo by Jamie McCarthy/NEP/Getty Images for Hired Gun Publicity & Consulting)

MIAMI BEACH, FL - OCTOBER 31: Kim Kardashian and Kanye West arrive at Kim Kardashian's Halloween party at LIV nightclub at Fontainebleau Miami on October 31, 2012 in Miami Beach, Florida. (Photo by Alexander Tamargo/Getty Images)

In this photo provided by Warner Bros., talk show host Ellen DeGeneres, left, reveals her Halloween costume in the likeness of actress Sofia Vergara, right, during the taping of "The Ellen DeGeneres Show" on Tuesday, Oct. 30, 2012, in Burbank, Calif. The special Halloween episode airs on Wednesday. (AP Photo/Warner Bros., Michael Rozman)

Adam Brody, Rachel Bilson, Josh Schwartz and Melinda Clarke at the SKYY Orange Party (Photo by J.Sciulli/WireImage for The Rose Group)

Martha Stewart arrives at "Hub Network's First Annual Halloween Bash" on Sunday, Oct. 20, 2013, at the Barker Hanger in Santa Monica, Calif. The star-studded special will be broadcasted on the Hub Network on Saturday Oct. 26, 2013. (Photo by Jordan Strauss/Invision for the Hub/AP Images)

Heidi Klum attends the 2013 Heidi Klum Halloween Party dressed as an elderly woman, at Marquee on October 31, 2013 in New York City. (Photo by Andrew Toth/FilmMagic)

Iggy Azalea dressed as Cruella de Vil attends the VEVO Halloween showcase at The Oval Space on October 31, 2013 in London, England. (Photo by Gareth Cattermole/Getty Images)

Model Alessandra Ambrosio, dressed as the Queen Of Hearts, attends the Casamigos Halloween Party at the home of Mike Meldman on October 25, 2013 in Beverly Hills, California. (Photo by Jerod Harris/Getty Images)

Kim Kardashian, dressed as Poison Ivy, attends the Midori Green Halloween costume party at Lavo on October 29, 2011 in New York City. (Photo by Rob Kim/FilmMagic)

Scott Disick (dressed as Robin) and Kourtney Kardashian (Dressed As Batman) arrive at Kim Kardashian's Halloween party at LIV nightclub at Fontainebleau Miami on October 31, 2012 in Miami Beach, Florida. (Photo by John Parra/WireImage)

Singer Pink, dressed as a clown, arrives at Heidi Klum's 2008 annual Halloween party at 1OAK on October 31, 2008 in New York City. (Photo by Charles Eshelman/FilmMagic)

Bethenny Frankel, dressed as Marilyn Monroe, attends Heidi Klum's Halloween presented by Shutterfly at Marquee on October 31, 2013 in New York City. (Photo by Andrew H. Walker/Getty Images for Shutterfly)

Actress Dascha Polanco, dressed as the Black Swan, attends Shutterfly Presents Heidi Klum's 14th Annual Halloween Party sponsored by SVEDKA Vodka and smartwater at Marquee on October 31, 2013 in New York City. (Photo by Cindy Ord/Getty Images for Heidi Klum)

Stylist June Ambrose, dressed as Queen Elizabeth, attends the 2013 Heidi Klum Halloween Party at Marquee on October 31, 2013 in New York City. (Photo by Andrew Toth/FilmMagic)

Model Shanina Shaik, dressed as Princess Jasmine attends the 2013 Heidi Klum Halloween Party at Marquee on October 31, 2013 in New York City. (Photo by Andrew Toth/FilmMagic)

Alexa Chung, dressed as Marie Antoinette, attends the Browns Focus Halloween party hosted by Alexa Chung at St Banabas House in Soho on October 31, 2008 in London, England. (Photo by Dave M. Benett/Getty Images)

Dressed as sexy Elvira and a ghastly ghoul

Heidi Klum arrives at her 12th Annual Halloween Party in Las Vegas. (2011)

Heidi Klum, dressed as Cleopatra, attends her Haunted Holiday Party benefiting Superstorm Sandy relief efforts, on Saturday, Dec. 1, 2012 in New York. Klum's original party, scheduled to be held on Halloween, was postponed due to the storm. (Photo by Charles Sykes/Invision/AP)

Darren Criss is a boy scout and probably a big fan of "Moonrise Kingdom."

We never thought we'd say it, but the "Jersey Shore" star and her fiancé positively geeked it out.

No sleight of hand here. Christina Milian is the Queen of Hearts.

George Clooney's girlfriend is "Black Swan."

Pop starlet Miley Cyrus' mum and sister Tish Cyrus and Brandi Cyrus are all dressed up for Halloween as they head to the Roosevelt hotel for a party in Hollywood.

Sacha Baron Cohen donned a bizarre monkey-cow costume.

P. Diddy rocked out at the Playboy Mansion Halloween Party in Beverly Hills, California on October 27th, 2012.

Brandon Davis at the Playboy Mansion Halloween Party in Beverly Hills, California on October 27th, 2012.

Lucy Hale as a unicorn.

In this Image released by Mattel, actress Shenae Grimes, from the series "90210", left, has a fitting of her Monster High Frankie Stein Halloween costume created by "Project Runway" alum Chris March, Wednesday, Oct. 17, 2012, in El Segundo, Calif. Grimes will be attending "Glee" cast member Matthew Morrison's 3rd Annual Halloween Bash, dressed as Frankie Stein, daughter of Frankenstein, from the popular Monster High franchise. This year, the popular Halloween party will be sponsored by Monster High. (AP Photo/Mattel, Rene Macura)

Heidi Klum gets fitted for her 13th annual Halloween party at finale sponsored by HobNob Wines, Svedka Vodka And Smartwater on September 3, 2012 in New York City.